Apparatuses conventionally used to take energy out of combustion gas produced by combustion of fuel include gas turbines. In gas turbines, for example, the turbines are rotated with the energy of combustion gas produced by combustion with compressed air supplied to combustion, thereby causing a rotor to output rotational energy.
For example, Patent Document 1 discloses a gas turbine with a rotor for high-speed rotation including a thrust bearing collar in an overhang provided outside a bearing span. The rotor is so configured that no shaft extends outside of the thrust bearing collar and the shaft of the overhang is made hollow, thereby simplifying the vibration properties of the rotor at a rated speed and facilitating balancing.
Patent Document 1: Japanese Patent Application Laid-open No. H5-118201